The present invention relates to an imaging apparatus and an imaging method. More specifically, the invention relates to an imaging apparatus and an imaging method for supplying an optimum amount of image data to another apparatus.
The popularization in recent years of imaging apparatus, such as digital video cameras, has entailed significant improvements in the resolution of camera equipment, such as the incorporation of a CCD (charge-coupled device) in each apparatus. There also is a recent trend toward a growing number of feature-rich models of imaging apparatus represented by digital video cameras furnished with a communication function and mobile phones with an imaging function.
Typically, a digital video camera equipped with a USB (Universal Serial Bus) communication function is capable of obtaining moving image data about a given object and supplying the moving image data thus acquired in real time to another apparatus, such as a personal computer, via a USB cable.
The higher the camera resolution, the greater the amount of moving image data obtained by imaging the object.
Where a data-receiving destination apparatus has a low processing capability or where network congestion between the sending and the receiving apparatuses are lowering transfer rates, the growing data quantity can lead to overflows of communication processes or missing frames in reproduced moving images.
A proposed solution to these problems involves causing the data-sending digital video camera to reduce beforehand the amount of outgoing moving image data, such as by compressing the data, so that moving image data can be supplied normally to their destination at reduced transfer rates. This solution, however, unnecessarily degrades the quality of reproduced moving images in cases where high-speed communication is available.
Another proposed solution involves preparing two kinds of data, i.e., first data, and second data acquired by compressing the first data. When the transfer rate is high the first data is supplied, but the lower quality second data can be supplied if the transfer rate turns out to be low. (For example, refer to Japanese Patent Laid-open No. 2002-99393, pp. 4-12, furnished with FIG. 4.)
The second solution has its own disadvantages. Because the two categories of data (i.e., first image data, and second image data which correspond to the first in content and which have the smaller quantity) need to be provided in advance, an ever-growing storage area must be allocated to accommodate the data to be supplied. Another disadvantage is that the second solution is not fit for applications where moving image data about the object are to be supplied in real time.
A further disadvantage is that the compression rate of the prepared second image data may or may not be suitable for the ongoing status of communication.